DE1568452A1 - Process for the preparation of compounds with protected amino groups - Google Patents

Description

Process for the preparation of compounds with protected amino groups

The invention relates to a process for the production of new compounds with protected amino groups.

Peptides are usually made by basically combining two or more amino acids in such a manner be linked so that an amide bridge is formed between the molecules. Since amino acids are at least bi- ' are functional, it is necessary to include in a given amino acid all functional groups that are not are directly involved in the amide linkage reaction, prior to this linkage step in an inactive state convict. Allowing such reactive functional groups to remain present will result the presence of large amounts of undesirable by-products from the interaction of these functional Groups lower the yields and make purification steps more difficult. There are already different possibilities known to convert the functional groups of simple amino acids into an inactive one by protecting groups in such catfish State that only the desired

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UnUiruigtiM f "'*"·.; · Μι. ι Sau 3 de » "<■. , ^ runosg-. ·;,. v. 4,9.196.?,

functional group for the implementation in the formation of the amide bond is available. It is necessary, that the so-called "protective group" is easily linked to the amino acid before the Araid formation and from the formed Peptide easily removed after condensation without cleavage of the newly formed amide bond can be. As N-standing protective groups, that is, groups that involve the Araino component in the reaction prevent, for example benzyloxycarbonyl, trityl, allyloxy and similar groups are already used.

The benzyloxycarbonyl group is exemplary of the known protective groups in the N position. This group helps to educate a carbamate bond to the nitrogen atom and can be easily link with the amino acid according to known working methods. The one protected by the benzyloxycarbonyl group Amino acid is then used to produce a dipeptide, i.e. a molecule made up of two amino acid components used. After the protected amino acid has reacted to form the desired peptide bond, the Benzyloxycarbonyl group removed by hydrogenolysis or hydrolysis. These reactions favor the splitting of the Carbamate bond that forms the protecting group and leave the peptide bond intact. · The reactions involved however, are equilibrium reactions and usually cause some amide bond cleavage.

Surprisingly, a method of production has now been found new protected amino compounds found, with the terminal amino groups of amino acids are protected can, whereby the use of such protected amino acids for the production of peptides and similar compounds is made possible. The amino protecting group can after

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the process according to the invention easily produced and are linked with the amino acid and then again almost quantitatively and without the addition of acid and Base can be removed from this.

The invention relates to a process for the preparation of compounds of the general formula

OR R ¹ 0 tt tt Il

CH ₅ - O - • C - N - C - O - OH

in which R alone is a hydrogen atom or an alkyl group with 1 to 4 carbon atoms, R ₁ alone is a hydrogen atom, an alkyl radical with 1 to 4 carbon atoms, a hydroxy-substituted alkyl radical with 1 to 4 carbon atoms, a carboxy-substituted alkyl radical with 1 to 4 Carbon atoms, an "alkyl radical with 1 to 4 carbon atoms substituted by a lower alkyl mercapto group, a guanidine-substituted alkyl radical with 1 to 4 carbon atoms, a guanidinoxy-substituted alkyl radical with 1 to 4 carbon atoms, an imidazolylmethyl group, an indolylmethyl group, a thienyl radical, a puryl radical or a benzyl radical or R and R together with the atoms to which they are bound represent a piperidine or pyrrolidine ring, characterized in that a compound of the formula

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If

CH ₂ -OCR ²

ρ
in which R is a halogen atom, an azido group or a p-nitrophenoxy radical, with a compound of the formula

RR ¹ 0

Tim.

H-N -C - C - OH

H
in which R and R are as defined above.

The above-mentioned alkyl radicals with 1 to 4 carbon atoms include, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, see. Butyl and tert-butyl radicals. Examples of lower alkyl groups are the methyl, ethyl, n-propyl and isopropyl groups; Lower alkoxy groups are, for example, the methoxy, ethoxy, n-propoxy and isopropoxy groups. Halogen atoms are for example fluorine, chlorine and bromine and lower alkyl mercapto groups, the methylthio, ethylthio, n-propylthio and isopropylthio group.

The compounds used according to the invention as starting materials or obtainable as products, as described above contain well-known

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■■ - · 5 - * ■ '· ■■

organic radicals or substituents, where in particular R ¹ can mean, for example, a phenyl or benzyl radical or certain heterocyclic radicals, but it should be noted that such radicals can have one or more substituents. Examples of such substituents consisting of single atoms or groups are phenyl, halogen, lower alkyl, lower perhaloalkyl, lower alkoxy, lower alkyl mercapto, cyano, acetyl-j, acetamido, hydroxy-j, -hydroxymethyl-, β -Hydroxyäthylsubstituenten and similar groups.

As examples of compounds obtainable according to the invention the following individual compounds may be mentioned: N-3,5-dimethoxybenzoxycarbonyl-L-tyrosine, N-3,5-dimethoxybenzoxycarbonylalalin, NO ^ -dimethoxybenzoxycarbonyl-phenylalanine, N-3,5-dimethoxybenzoxycarbonyl-oleamine ^ n-butyric acid, N-3> 5-dimethoxybenzoxycarbonyl-D-valine, N-3,5-Dimethoxybenzoxycarbonyl-2,4-dichlorophenyl alanine and N-3,5-dimethoxy.benzoxycarbonylod. " amino adipic acid.

The protected amino acids are prepared as follows: 3j5-dimethoxybenzyl alcohol is reacted with phosgene in the presence of an acid acceptor, for example dimethylaniline, pyridine or the like, to form 3> 5-dimethoxybenzyl chlorocarbonate. In order to obtain the protected amino acid, the chlorocarbonate can be reacted directly with the amino acid. However, it can also first be converted into the azide by known procedures, for example by reaction with hydrazine and subsequent diazotization with an inorganic nitrite. The azide is then reacted with the amino acid by known methods

2 09811/182 3 ORIGINAL BATHROOM

of azides reacted with amino compounds. Furthermore, the 3,5-dimethoxybenzyl alcohol can first be treated with p-nitrophenyl chlorocarbonate in the presence of an acid acceptor, for example pyridine, dimethylaniline or the like, converted into the p-nitrophenyl carbonate derivative and then with the amino acid in the presence a basic agent, for example aqueous sodium hydroxide solution.

The protected amino acid is used to manufacture peptides according to one of the various for the manufacture known methods of such compounds are used. For example, you can have the protected amino acid in it Acyl halide convert to that with an amino acid a dipeptide or with a polypeptide can be converted into a polypeptide different therefrom. then the protective group is removed from the amino group in order to make this further reaction accessible.

After the protected amino compound with a another amino acid or a peptide or a similar compound can be used as the protective group easily remove by removing the formed compound from a UV light source, for example a mercury vapor lamp 'suspends. The compound from which the protecting group is to be removed is in before irradiation dissolved in an aqueous medium or in an aqueous-organic medium. The compound that makes up the protecting group is then recovered by any convenient method.

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BATH ORIGINAL

3,5-Dimethoxybenzyl-p-nitrophenyl carbonate, which can be used according to the invention to protect amino groups, can be prepared as follows: an ice-cold solution of 28.0 g (0.167 mol). 3,5-Dimethoxybenzyl alcohol and 5.90 g (0.150 mol) of pyridine in 100 ml of acetone are admixed with 30.4 g (0.150 mol) of p-nitrophenyl chloroformate while stirring. The resulting slurry is added to 700 ml of water, the pesticide is filtered off, washed several times with water and recrystallized from 2500 ml of methanol. 30.7 g (61 %) of 3,5-dimethoxybenzyl-p-nitrophenyl carbonate, melting point 114 ° to 115 ° C., are obtained.

Example 1 N-3,5-Diniethoxybenzyloxycarbonyl-D-phenylglycine

A mixture of 3.66 g (0.024 mol) D-phenylglycine, 10.0 g (0.030 mol) 3,5-dimethoxybenzyloxy-p-nitrophenyl carbonate, 24.0 ml of 2N sodium hydroxide solution and 48 ml of tetrahydrofuran are stirred for 21 hours at room temperature. After the tetrahydrofuran has been evaporated off under reduced pressure, the precipitated pesticide is filtered off and washed several times with 1 M aqueous sodium bicarbonate solution. You put the combined filtrates with 1 η hydrochloric acid to pH 5.8 and extracted the. obtained mixture three times to remove p-nitrophenol and unreacted 3s5-dimethoxybenzyl-p-nitrophenyl carbonate with ether. The aqueous phase is then covered with a layer of ether and acidified to pH 2.0. The ether layer is withdrawn and the aqueous layer is made twice more

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extracted with ether. The combined ether extracts are washed twice with water and once with saturated sodium chloride solution and dried with sodium sulfate. Evaporation of the solvent and recrystallization of the residue from methanol / water is obtained 6.40 g (77%) of 3,5-dimethoxybenzyloxycarbonyl-D-phenylglycine, P. 130 to 132.5 ⁰ C. The protected D-phenyl · 'glycine can be converted to dipeptides or polypeptides with other amino acids or peptides by known methods.

In Table I below are various physical constants of other protected amino acids that are used after above procedure are available, listed. Furthermore, as described above, the chlorocarbonate and the acid can also be reacted by known methods for producing protected amino groups.

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O 20981 amino acid Z - * Glycine 1823 !
m DL-methionine 1 * 1
α L-serine C -C carbobenzoxy L-lysine

Table I.

3,5-Diinethoxybenzyloxycarbony! Derivative

Yield 71.Ji; P. 97 to 98 ⁰ C; Neutral equivalent
calc .: 269; found: 26 * 1

Yield 68 %; M.p. 86 to 88 ° C; Neutral equivalent
calc .: 3 ^ 3; found: 337

Yield 55 %; P. ¹ ^ J to 56 ° C;

+ 15 ", 0

(C 1.02) neutral equivalent calc.: 299; found: 296

Yield 7% ¹ I i P. 120.5 to 121.5 ° C; fpCT ^ ⁷ + 11.7
(CHCl ₃ , C 1.02); Neutralization equivalent: calc .: * J75;
found:

* CD I OO

Example 2 N-S ^ -Dimethoxybenzyloxycarbonyl-D-phenylglycylglycine

A solution of 1.38 g (0.004 mol) of 3,5-dimethoxybenzyloxycarbonyl-D-phenylglycine in 20 ml of tetrahydrofuran was cooled in an ice-salt bath, mixed with 0.56 ml of triethylamine and then with 0.52 ml of isobutyl chloroformate Stirred for 15 minutes. Then a cold solution of 0.300 g (0.004 mol) of glycine and 0.56 ml of triethylamine in 20 ml of water / tetrahydrofuran (1: 1) was added dropwise and the mixture was stirred for one hour in the cold and one hour at room temperature. After removing the tetrahydrofuran under reduced pressure, the residue was diluted with 20 ml of water and washed once with 20 ml of ethyl acetate. The aqueous phase was separated off, diluted with ko ml of water, covered with a layer of ho ml of ethyl acetate and the pH was adjusted to 2.5 with 10 # hydrochloric acid. The aqueous phase was then extracted once more with 40 ml of ethyl acetate. The combined ethyl acetate extracts were washed once with water and dried with anhydrous sodium sulfate. The solid residue obtained after evaporation of the solvent was slurried with ether and filtered, whereby 1.16 g (72 %) 3 ^ 5-dimethoxybenzyloxycarbonyl-D-phenylglycylglycine, P. 156 to 157 ⁰ C were obtained.

General procedure and device for irradiation

The protective group was removed by irradiation using a Hanau ÖS ^ A-Sö high-pressure mercury lamp.

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- ii -

taken with a filter jacket made of Vycor glass (Coming No. 7910) and placed in a water-cooled Quartz plunger was included. The compound to be irradiated is dissolved in 1 1 dioxane / water (1: 1) dissolved. During the reaction, nitrogen was bubbled through the solution / the irradiation time was 1.5 Hours. The course of the reaction was determined by paper chromatography tracked.

The deprotected compound, for example a peptide, was removed by evaporation of the Solution to dryness, treating the residue with a small amount of acetone and filtering off the product. In the following, the procedure used to remove the protective group is explained using an example.

A solution of 1.00 g (0.002 ^ 9 mol) of 3,5-dimethoxybenzyloxycarbonyl-D-phenylglycylglycine in 1 liter of dioxane / water (1: 1) was irradiated for 1.5 hours. The solution was evaporated to dryness and the residue was treated with a small amount of acetone. The D-phenylglycylglycine contained in the residue crystallized and was filtered off and air-dried. The yield was 0.335 g (65 % of theory), P = 226 to 228 ^° C.

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Claims (3)

Claims or 2
CH ₂ -OCR CH, 0 * - in which R alone represents a hydrogen atom or an alkyl group with 1 to ² carbon atoms, R ₁ alone represents a hydrogen atom, an alkyl radical with 1 to 4 carbon atoms, a hydroxy-substituted alkyl radical with 1 to 4 carbon atoms, a carboxy-substituted alkyl radical with 1 to k Carbon atoms, an alkyl radical with 1 to H carbon atoms substituted by a lower alkyl mercapto group, a guanidine-substituted alkyl radical with 1 to A carbon atoms, a guanidine- 209811/1823 INSPSCTED . Oxy-substituted alkyl radical with 1 to k carbon atoms, an imidazolylmethyl group, an indolylmethyl group, a thienyl radical, a furyl radical, a phenyl radical or a benzyl radical or R and R together with the atoms to which they are bonded a piperidine or pyrrolidine ring and Rg a mean p-nitrophenoxy radical. 2. Compounds according to claim 1, namely N- (3,5-dimethoxybenzyloxycarbonyl) glycine; N- (3,5-dimethoxybenzyloxycarbonyl) methionine; N- (3 »5-dimethoxybenzyloxycarbonyl) phenylglycine; or N- (3,5-dimethoxybenzyloxycarbonyl) serine. 3. Method of making peptides using of compounds: with a split amino group, characterized in that a compound with protected Amino group a compound of the general formula 0 RR ¹ 0 «It H CH ₉ -OCNCC-OH in which R and R are as defined in claim 1, is used . 209811/1823